Polyurethane binder refers to an adhesive containing urethane groups (-NHCOO-) or isocyanate groups (-NCO) in the molecular chain. Polyurethane adhesives are divided into two categories: polyisocyanate and polyurethane. Polyisocyanate molecular chain contains isocyano group (-NCO) and urethane group (-NH-COO-), so polyurethane adhesive shows a high degree of activity and polarity. It has excellent chemical adhesion with substrates containing active hydrogen, such as foam, plastic, wood, leather, fabric, paper, ceramics and other porous materials, as well as metals, glass, rubber, plastics and other materials with smooth surfaces.